There are systems known, which have been developed for micro processing an object by laser ablation and subsequent focused ion beam (FIB) preparation.
Laser ablation processes allow to achieve high ablation rates, compared to processing procedures, which rely on ion beams. These high ablation rates allow effective application of these processes in biosciences, quality assurance and process control procedures. Quality assurance and process control procedures are largely applied in semiconductor manufacturing processes.
High ablation rates also make it possible to expose large cross-sectional areas of the object, which are buried deeply below the surface of the object. Thereby, time-efficient inspections of complex semiconductor structures, such as multiple stacked ICs and 3D MEMS, can be performed.
Typically, the laser system is arranged outside of the preparation chamber and the laser beam is introduced into the interior of the preparation chamber through a transmission window mounted to the preparation chamber.
Performing the laser ablation processes in the interior of the preparation chamber typically causes contamination on the vacuum-side surface of the transmission window. However, also the atmosphere side surface may suffer contamination from ambient air.
Such a contamination may lead to a lower light intensity of the laser beam reaching the object, or may even lead to destruction of the transmission window caused by the heat introduced by the laser beam impinging on the low-transmissive window. High contamination levels typically occur during routine use of the processing system for process control. In order to ensure operability of the processing system, the transmission window has to be removed from the processing system and cleaned on a regular basis.
Moreover, also the typical levels of thermal stress, which is introduced into the transmission window by the laser beam, require to check the condition of the transmission window.
Hence, it is desirable, to provide a processing system for laser micro processing, which allows easy maintenance or replacement of a laser transmission window.